Open-top refrigerator display case



July 13, 1954 w. scHMlD-r 2,683,355

OPEN-TOP REFRIGERATOR DISPLAY CASE Filed Jan. 24, 1951 TTOF/VEXS'.

Patented July 13, 1954 OPEN-TOP REFRIGERATOR DISPLAY CASE Walter Schmidt, Roeland Park, Kans., assignor to Koch Butchers Supply Company, North .Kansas City, Mo., a corporation of Missouri Application January 24, 1951, Serial No. 207,486

2 Claims.

This invention relates to open top refrigerator display cases and particularly those utilizing natural convection currents in effecting refrigeration of the articles on display. Cases of this character are particularly desirable for selfservice stores, but they have presented many problems such as display of the merchandise at a too great a depth below the open top of the case, frosting over of the merchandise and refrigerating surfaces, defrosting of the refrigera ting surfaces without first removing the merchandise on display, too high temperature of the merchandise on'display, inability of maintaining a body of chilled air over the merchandise and for many other reasons well known to refrigerator manufacturers.

It is the purpose of the present invention to overcome these difficulties by providing such cases with an auxiliary refrigerating element located in an out-of-way position within the display ycase and arranged for `effecting transfer of heatl from the exposed surfaces of the articles o n display to the refrigerating element by radiation and convection; to provide the auxiliary refrigerating element with surfaces in proximity to warm, moisture-laden exterior air that may enter the open top of the refrigerated display case and on which the moisture collects in vthe form of frost before contact thereof with the exposed surfaces of the merchandise on display and/or surfaces of the main refrigerating elements; to provide for mum and effectivecirculation of convection currents over the exposed surfaces of the displaye merchandise.

In accomplishing these and other objects of the invention as hereinafter pointed out, I have provided improved structure the preferredform of which is illustrated in the accompanying drawings wherein:

`Fig. 1 is a perspective cross sectional View of an open top display case constructed in accordance with the present invention.

Fig. 2 is a cross section through the display case particularly illustrating the convection currents set up by the auxiliary refrigerating element and heat radiation from the articles on display when the case is in operation.

Fig. 3 is an enlarged fragmentary cross section, particularly illustrating the auxiliary refrigerating element and the heater to effect defrosting thereof.

Referring more in detail to the drawings:

l designates a refrigerator display case constructed in accordance with the present invention and which includes a base 2 supporting a display section 3 comprising suitably insulated front, rear, and end walls 4, 5, 6, and a bottom l to form a display compartment 8 having an open top 9. The rear wall 5 extends above the front wal1'4 and terminates in an insulated top wall portion l'that extends forwardly over a portion of the display compartment. The top portion I0 carries a canopy section Il which has an upwardly and forwardly inclined mirror panel IZ for reflecting the merchandise on display in the display compartment. A portion of the canopy extends forwardly of the upper portion of the mirror panel to house an illuminating element (not shown) as in conventional practice. The forward'edge portiony I 3 of the horizontal wall IQ carries a rearwardly inclined horizontal rail I4 adapted to carry price tags or other information concerning the merchandise on display.

yThe end Walls 6 extend upwardly substantially in plane with the horizontal wall portion l0 and carry transparent wings l5, as best shown in Figs. 1 and 2. Extending along the upper edge of the front wall l is a transparent wall extension i6 formed by a frame carrying a plurality of spaced transparent panels Il to promote display of the articles in the refrigerating compartment, the upper edge of the transparent panels terminating substantially in plane with the lower part of the horizontal wall portion I0 as best shown in Fig. 2. The space between the rail I4 and the transparent panelsection Il provides a top opening 9 through which the merchandise on display is inserted and removed from the display compartment. The display compartment is divided transversely into a plurality of spaces I9 by means of plate type refrigerating elements 2t]l having refrigerant supply and return ducts 2l and 2l connected with a suitable refrigerating unit that may be contained in the base 2. The articles to be displayed are contained within the respective spaces up to substantially the level of the upper edges 22 of the main refrigerating elements 20, as best shown in Fig. 2.

The problems in the structure thus far described is that of providing sufficient refrigeration for the top or exposed surface of rthe articles or products being displayed. This is particularly true of frozen food and ice cream because of the large difference between ambient temperature conditions or those outside of the display case and the temperature required for the proper storage ci such products. The temperature of the product can be partially controlled by limiting the lling or the spaces i9 so that the exposed surfaces of the display are considerably below the open top of the case. However, this defeats the purpose of an open type display case since the advantage thereof is the display of the goods in such a mannerithat they can `be. readilypseen and easily reached by the-customers in a self service store.

It is therefore obvious that a successful display case must be a good productrpreseryeriand yet .have the top surface of the displayed articles close to the top openingpoigthev xture andato maintain the exposed surface offthe-fproducts Y frigerator coils .which AareuSurfrlly,locatedrabove the refrigerating elements arenotneoessary.

In carryingoutv the invention,. the display. ,case

is provided withan auxiliary reiri-gerating .ele, .ment-23 .that is .located within theangle :formed between the rear wall 15. andthe; horizontallwall .portionii of .thecaseandzwhich eXtends;,the full length thereofsofthat it is effectivepreserving Asurface temperatures vin the upper. portions. of all .ofA the displayspaces. In .the illus- `trated instance, the Aauxiliary .reirigerating element is of the. plate type :inoludinga:preferably `metallic jaclretz@having frontend rearnvalls-.Z

and'26 interoonnectedat .the sides and ...upper-.- and lower edges*` to l'form .an-enclosurehavingl ,a

Lrefrigerating coil 21. trated instance, is `shown asv connected: between the refrigerant-supply'.duct 2l`and thecoils28 -of the main refrigeratingelernents. ,The auxil- Y O f dicated by thevarrows designatedl:inl Figgz.-

The position .of the auxiliary refrigeratingselement Ialso Vefects'vanatural convection; current of airinnthe direction --ofV the' arrows designated 30 to pick` up heat from` the `producesurfaceand carry-itto the `refrigerated surface ofthetauXi-l- -iary heating element. 4As the. convection .c urrents pass over the `reirigerating -surface any moisture received `from the outside air-entering thecase, indicated bythe -arrowsfdesignated L8, is Avrst carried over the...surface-ofthe coil so that it isdeposited thereon in the ltorm .fof frost. Therefore, the air which moves-across: the.y surface of the products onrdisplaylis dehydratedand free of moisture so that there isi-little or: rio-deposit on the main refrigerating elementsor on the exposed surfaces of the merchandise. vThe circulation of the air and radiation as thus `described is sufficient to maintain the desired temperature of the surfaces-of the products on display so as-to assure the temperature required 4in preserving such'products as ice cream, 'frozen foods and the like.

It is thus obvious that the auxiliary coil collects the moisture in the formrof frost andminirnizes or excludes frostaccumulation on the mainKV refrigerating elements; consequently, thereisvno necessity of defrosting .the .main refrigerating elements. The auxiliary -elementniay be connected in series with the corresponding coilsof the main refrigerating :elementsand the temperature thereof is preferably maintained at a lower temperature so as to assure the moisture to collect on the colder surfaces thereof. However, if the auxiliary plate temperature is equal to or slightly higher than the main refrigeration elements, the auxiliary element will still collect frost because of its proximity to the entering .,.gmoistr air. ""Thei frost accumulates on` the surrface of *theauxiliary--refrigerating element and is readily removed by means of an electrical Vthea-ter 3i that is carried in contact with the rear suriace-- ofl-,theauxiliary element and which is supplied with a suitable electric current through 1.-conductorsf32 andSB. Connected into one of the -foonductors'sis-a time control switch 3ft so as to automatically` and` periodically establish the currenti.flow-.throughthe heating element so as to melt 01T any frost that has accumulated beitweenfthe time periods. The melted frost ows down the refrigeratinga surface and collects in a itroughf, .35; that is :.positionedvcoeextensively `with the. Y,auxiliary refrigerating ...element Land yfrom fwhich. thezz-water is. discharged through, a `drain .pipe raslzbestshown infsFg-- 3- sTests indicate that adisplay case operating .with the Aauxiliary refrigerating elementincon- `junctionwith the y-rnain;refrigBra't-lag :elements .can hold exposedrsuriacetemperatures .or the product .at-0 while .without the/.auxiliary y.refrigeratng velement'Jandia-1l ,other condi-tions being; .the sama-, the .temperature isapproximately +9 F. This is:electedfthroughrtransfer of rheatirom; .the producten-display .tothe-refrigerated-surface Vof; the; auxiliary l,element. -,by,-ra-diation, convectiongand. conduction.

It is also obvious that theiaauxiliary;refrigerating-element 'provides a surfacefor the? accumuy,lationwoi frostcandfdehydrates'-the convection vcurrents-oi air. 'The accumulative frost. may be readilyv :removed therefromeither.- automatically,

as'shown,kor manually with-the use of-a scraper (notshown).

\ What VI claim and` ,desire to: Secure by Letters n Patent is:

,1. A 'vdivsplayase having iront, rear and end wallsandfa top wall terminating VAinwardly'from the rear wall in'ltrhedirection ofthe front wall to cooperate with ,upper portions ofsail side and front vwallsinforming an opening to a display compartment withinfsaidgca'se, refrigeratjin'gV elements in'A thedisplay compartmentfhaving upper portions terminatingsubstantially' at the surface `levelpofgoods tobe contained said display' compartmena and an auxiliaryrefrigerating element extending alongthe rear-wall' and` having a substant-ially flat yreadily' conductive surface inclined upwardly from the rear wall substantiallyr at the level-of said upper portions of the refrigerating eements and terminating substantially at the terminal edge of said-.top wallin 'direct-contact byv exterior air that yenterszthe open top of the compartment to relieve said entering iair ofmoisture inLthe formzoifrostonsaid surface of-the refrigerating element for diverting Ythe .dried air downwardly over usaidsurface .of .thefgoodal for Mcirculation within saidfopen,..top byconvection currents, said surface ofthe auxiliary refrigeratingrelementbeing arranged relatively to a horizontal planefthroughsaid case forA absorbing heat relected'from the surface of goods in said' plane.

2. A display case` having front, rear and end walls and a top wall terminating inwardly from the rear wallinthe direction'of'the front wall to cooperate'fwith upper portions `of saidfside4 and front walls in forming an opening to a :display compartment within said case, refrigerating elements in the display compartment having upper portions terminating substantially at the surface level of goods to be contained in saiddisplay compartment, an auxiliary refrigerating element extending along the rear Wall and having a suby stantially nat readily conductive surface inclined upwardly from the rear wall substantially at the level of Said upper portions of the refrigerating elements and terminating substantially at the terminal edge of said top Wall in direct contact by exterior air that enters the open top of the compartment to relieve said entering air of moisture in the form of frost on said surface of the refrigerating element and for diverting the dried air downwardly over said surface of the goods for circulation within said open top by convec'- tion currents, said surface of the auxiliary refrigerating element being arranged relatively to a horizontal plane through said case for absorbing heat reflected from the surface of goods in said plane, said auxiliary refrigerating element forming with said top and rear wall a closed space, and a heating element in said space to heat the auxiliary refrigerating element to melt the frost therefrom.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,207,586 Hill July 9, 1940 2,271,802 Nordskog Feb. 3, 1942 2,430,329 Davis Nov. 4, 1947 2,465,934 Sanders Mar, 29, 1949 2,474,130 Tully June 21, 1949 2,534,488 Weber Dec. 19, 1950 

